This invention relates to an apparatus and method for twisting individual strands of yarn and plying these individually twisted strands around each other, and the yarn made according to the method. More specifically, this twisting action is accomplished by false-twisting, where for a certain yarn length the yarn is twisted a number of turns in one direction and then for another sequential length, it is twisted in the opposite direction. The application also discloses yarns produced according to the method and on an apparatus of the type described.
The nature of false twisting is such that the total number of turns in one direction minus the total number of turns in the opposite direction over the total yarn-length is zero. The method of taking several twisted yarns and combining them by twisting them together to make a multi-stranded yarn has been known for thousands of years. However, plying previously-twisted yarns together is energy and time-consuming, since for every turn in the individual yarn and also for every turn in the plied multi-stranded yarn, the yarn packages must be turned around their axis.
The apparatus and method according to the invention is much more economical since only a relatively short piece of each yarn is twisted around its own axis. The secondary plying occurs automatically since, through the inserted torque, the twisted yarns in the single yarn twist around each other in the direction of the yarn-torque.
The twist-inserting apparatus according to the invention is a simple and unique way of providing a twist-inserting jet of air to the moving yarn which is highly precise and reliable, and easily modified when changes in yarn construction or twist characteristics require.
It is therefore an object of the invention to provide a fluid-jet twist-inserting apparatus for inserting twist into a multi-stranded, plied yarn. Twist is inserted by twisting a section of a given length of each individual strand around its own axis where the downstream sides of the yarns have twist in one direction and the upstream sides have the same amount of opposite twist. The twist direction is alternated periodically, whereby at twist reversal locations the fibers of the individual yarns are xe2x80x9ctackedxe2x80x9d by, for example, a fluid jet such as an air-jet entangler.
It is another object of the invention to apply the twist to the individual yarns with stationary twisting elements as the yarns travel past the stationary twisting elements, whereby the direction of twist is periodically reversed.
It is another object of the invention to control the insertion of twist by means of compressed air supplied by twist-inserting air-jets connected to solenoid valves, which are controlled through an electronic controller.
It is another object of the invention to provide that the amount of twist in one or more yarns are varied over the length of the plied yarn.
It is another object of the invention to provide a twist-inserting apparatus which makes use of a limited number of identical or similar disks.
It is another object of the invention to provide a twist-inserting apparatus wherein the amount of air being applied to the yarn can be varied by adding or removing one or more like components.
It is another object of the invention to provide a twist-inserting apparatus which is compact and has no moving parts.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an apparatus for inserting twist into a moving strand, comprising a first body which has an orifice extending therethrough for permitting passage of a moving yarn, and has an air channel extending therethrough and communicating with the orifice.
The air channel communicates with the orifice at a tangentially-offset angle to the path of the yarn through the orifice to create a cyclonic air circulation pattern in the orifice to insert a predetermined direction of twist into the yarn as the yarn passes through the orifice. The first body is adapted for being inverted relative to, and placed in overlying registration with, a second like body whereby the air channel of the first body inserts one predetermined direction of twist into the yarn and the air channel of the second body inserts another predetermined direction of twist into the yarn.
According to one preferred embodiment of the invention, the first body is disk-shaped, the orifice extends in an axial direction through the body, and at least a portion of the air channel extends radially through the body.
According to another preferred embodiment of the invention, the disk includes a plurality of spaced-apart orifices and a plurality of air channels, one of the plurality of air channels communicating with a respective one of the orifices.
According to yet another preferred embodiment of the invention, the orifices are clustered in a central area of the body and the air channels extend radially inwardly towards the orifices from a peripheral area of the body.
Preferably, at least four symmetrically-spaced orifices are formed in the body, and at least four air channels extend radially-inwardly from a peripheral area of the body into communication with a respective one of the orifices.
Preferably, each of the air channels intersects the respective orifices at a right angle to the direction of yarn travel.
According to yet another preferred embodiment of the invention, selection means are provided for selecting one or the other of the first body or second body air channels to deliver air to the respective first or second orifice and thereby insert a predetermined direction of twist into the yarn.
According to yet another preferred embodiment of the invention, the first body comprises a circular disk having opposed first and second major surfaces. The apparatus also includes a top end block and a bottom end block between which the first and second disks are sandwiched, and air supply ports extending through the top end block and communicating with respective air channels in the first and second disks.
According to yet another preferred embodiment of the invention, the air channels extend through the thickness of the body and communicate with the opposed first and second major surfaces.
According to another preferred embodiment of the invention, the air channel communicates with the orifice through a respective air channel nozzle, and the area defined by the opening of the nozzle into the orifice is no more than one/fourth of the area of the orifice.
According to yet another preferred embodiment of the invention, the air channel communicates with the orifice through a respective air channel nozzle, and the area defined by the opening of the nozzle into the orifice is about one sixth of the area of the orifice.
According to yet another preferred embodiment of the invention, the air channel communicates with the orifice through a respective air channel nozzle, and the width of the nozzle is no more than one half of the width of the air channel.
According to yet another preferred embodiment of the invention, the air channel communicates with the orifice through a respective air channel nozzle, and wherein the width of the nozzle is no more than about one third of the width of the air channel.
According to another preferred embodiment of the invention, an apparatus for inserting twist into a moving strand comprises a first body, which includes an orifice extending therethrough for permitting passage of a moving yarn, an air channel extending therethrough and communicating with the orifice. The air channel communicates with the orifice at a tangentially-offset angle to the path of the yarn through the orifice to create a cyclonic air circulation pattern in the orifice to insert a predetermined direction of twist into the yarn as the yarn passes through the orifice. A second body is provided, which includes an orifice extending therethrough for permitting passage of a moving yarn, an air channel extending therethrough and communicating with the orifice. The air channel communicates with the orifice at a tangentially-offset angle to the path of the yarn through the orifice to create a cyclonic air circulation pattern in the orifice to insert a predetermined direction of twist into the yarn as the yarn passes through the orifice. The first body is inverted relative to, and placed in overlying registration with the second body. The top and bottom end blocks enclose the first and second bodies. The top end block includes air supply ports extending therethrough which communicate with respective air channels in the first and second disks for supplying pressurized air thereto. The air channel of the first body therefore inserts one predetermined direction of twist into the yarn and the air channel of the second body inserts another predetermined direction of twist into the yarn.
Preferably, the first body and the second body comprise respective first and second disks.
According to another preferred embodiment of the invention, the first and second disks each have a predetermined thickness defining a air channel dimension.
According to yet another preferred embodiment of the invention, the apparatus is adapted to receive first and second disks having different predetermined respective thicknesses for accommodating an air channel having a larger or smaller air flow capacity whereby first and/or second disks can be substituted in the apparatus to increase or decrease the air flow capacity required for a given yarn size, configuration or level of twist insertion.